Refractor Telescopes

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Well, as you can see, light enters the tube (right) and is refracted or bent, to come to a focus at the eyepiece. The primary lens, or objective is a convex piece of glass. The advantage of this over a reflector, is that the light is a straight through process and is not reflected by mirrors. Each time light is reflected, some light loss occurs. In a typical Newtonian reflector, there are two reflecting surfaces. This means that for the same aperture, the image is noticeably brighter in a refractor. The Refractor is much more expensive than a reflector. The reason for this is that the primary objective is usually not just one piece of glass. In order to overcome Chromatic aberration, the primary is made of several pieces of glass, each one is a different kind of glass (flint glass and pyrex glass) and each is ground differently. All of which adds to the expense of the system.

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